Find My Friends Geo fence

I really thought I'd seen this in a previous beta of iOS 6 and I've definitely read about it. Does anyone know if the geo fence feature in Find My Friends app has been removed or otherwise, how I use it?

I was having problems too, but I think I've figured it out. In order for it to work you have to have Passcode enabled on both phones. When Passcode is enabled you don't have to sign in to Find My Friends. I have my phone locked with Passcode and when I click on me the notify feature is available, my husband's phone isn't Passcode locked, when I click on notify it says not available. So I'm going to set up Passcode on his phone tonight and test my theory. I'll let ya know if that's the key.